Process and apparatus for purifying liquids deleteriously affected by air



PROCESS AND APPARATUS FOR PURIFYING LIQUIDS DELETERIOUSLY AFFECTED BYAIR T. H. MILLER Dec. 3, 1940.

PROCESS AND APFARATUS FOR PURIFYING LIQUIDS DELETERIOUSLY AFFECTED BYAIR 2 Sheets-Sheet 2 Filed July` 17, 1959 CENTRIFUGE Ja CENUYFUGE 0/1.K/wArE/ale Moog/0f@ Patented Dec. 3, 1940 UNI-TED STATES PROCESS ANDAPPAATUS FOR PUBIFYING LIQUIDS DELETEBIOUSLY AFFECTED BY AIR Theodoreluilier, Poughkeepsie, N. YC., assignor to The De Laval Separator CompanNew York,

t N. Y., a corporation of New Jersey Application July 17, 1939, SerialNo. 284,929

'l Claims.

My invention has for its object the removal of liquid impurities fromliquids that are deleteriously affected by mixture or contact with air.One example of such liquids is the oil from conservator or inert airtransformers which, if allowed to mix with or come in contact with air,will absorb therefrom oxygen that will afterward cause sludging in theoil and may cause corrosion of metal parts of the transformer.

My invention comprises an improved process and apparatus foraccomplishing this object.

I'he necessity for exclusion of air is a requirement particularly wellmet by "air tight puriers of the types shown in various U. S. patents,of which Nos. 1,101,548, 2,002,954, and 2,043,350 are examples, in whichthe liquid being puriiled is in completely enclosed spaces from the timeit leaves one tank until lt enters another one or returns to the sameone.

This type of centrifuge has no inherent control in the bowl, such asthere is in an ordinary open discharge centrifuge for this work, thatwill cause a cessation of discharge from the outlet for either the lightor the heavy constituent if there is none of that constituent in themixture being fed to the puriiler.

In the air tight centrifuges the ratiobetween the discharges from thetwo outlets must be regulated by throttle valves that control the backpressure on one or both outlets.

It is known that if, from a large quantity of oil containing a smallproportion of water, there are separated all the water with a smallquantity of oil, the water will gather together in such large drops thatit will quickly separate vby gravity if allowed to remain quiescent fora short time.

I have found that, if Il connect a liberal size pipe, 'from the heavyconstituent outlet of a centrifugal purifier, to a gravity separationtank containing a oat that will sink in oil but oat on water and soconnected with a drain in the bottom of the tank that it will open itwhen the tank is more than half full of water and close it when lessthan half full, and provide a small by-pass from the top of the tank tothe inlet to the pump feeding the puriiier, I can operate continuously.Whatever water is in the oil being treated will be separated in thepurier and ow to the gravity separation tank from which it will bedischarged by the iioat controlled valve.

A smallquantity of oil will flow with the water` to thetank andthencethrough the by-pass to the inlet to the pump where it will be returnedto the system. If there is no water in the oil being treated there willbe only oil circulating from the water outlet from the purifier/to andthrough the tank and the by-pass tothe pump. This stream of oil willcarry with it to the tank any water that may be subsequently separated 5from later quantities of oil. t

A I have also found that instead of the gravity separation tank I mayuse a centrifuge having a closed outlet for the lighter constituent andan open outlet for the heavy constituent. Because any heavy constituentthat reaches this centrifuge has. been once separated from the lighterconstituent, a major part of it can be easily reseparated in acentrifuge of low emciency, and because all light constituent from thiscentrifuge is repassed through the main centrifuge there is no need fora perfect separation of the heavier constituent from the lightconstituent.

In the accompanying drawings:

Fig. 1 is a flow sheet of an apparatus using a gravity separation tankfor the secondary separation.

Fig. 2 is a ow sheet of an apparatus using a centrifugal separator forthe secondary separation, and

Fig. 3 is a vertical cross-sectional view of a centrifugal bowl suitablefor use to accomplish the secondary separation.

Referring first to Fig. l: I is the enclosure for a transformer or otherdevice, containing liquid to be puried, from which a pipe 2 leadsthrough a valve 3 and a pump l to a centrifugal purier 5, in which theliquid being treated iscompletely enclosed from the air.

From the top of the purifier a pipe 6, with a valve l, conducts theseparated purified liquid back to the top of the tank I. From the top ofthe purifier `another pipe .8 conducts separated` heavier liquid,containing some lighter liquid, to a gravity separation tank Il havingtherein a float III which, as `it rises or falls, opens or closes avalve II at the entrance to a heavy liquid outlet pipe I2. From the topof the tank 9 a small pipe I3 with a valve Illeads back to the pipe 2between the valve 3 and the pump I. Pipe I5 with valve I6 and pipe Ilwith valve Il are provided to permit escape of air from the system whenstarting. A heater I9 is provided for use ifthe liquid from the tank Iis too cold for eillcient puriilcatlon.

Referring next to Fig. 2: The elements in Fig. 2 corresponding to thoseof Fig. 1 are similarly numbered, the reference numerals, however, beingfollowed by the reference letter a. The apparatus shownin Fig. 2 is thesame as that of Fig. 1 except that instead of the gravity separationtank l with outlets l2 for water and i3 for oil, there has beensubstituted a centrifuge 9a with spout |2a for water and pipe i3d foroil.

Referring next to Fig. 3; which is a vertical sectional viewf'ofthecentrifuge 9a: The spindle 2|, by which thebowl is supported and driven,has a central passage 22 through which the liquids from pipe 2a are fed.Passages 23 lead from the passage 22 to the outer part of the bowlwhence the liquids ilow into the spaces between the.discs 24 where theactual separation ltakes place. 25 is the outlet tube from the bowl forthe lighter constituent from below the top disc 26, 21 is a seal thatmakes a gas and liquid tight connection between the rotating outlet tubeand the stationary pipe ila. 28 is a control weir over which the heavyconstituent escapes from between the topdisc 26 and the bowl top 29 intoa collecting cover 30 discharging through the spout I 2a.

While the process and apparatus are applicable "for the purification ofmany liquids containing heavier impurities, both liquid and solid, IwillI describe `it as applied to the purification of insulating oil,from a transformer of the conservator or inert air` type, containingwater and solid impurities.

Assuming that the apparatus of Fig. 1 is used to practice the'process:When it is desired to purify the oil in the transformer I the pump 4 isstarted and the' valve 3 opened slightly to slowly ll the system withoil, while the air escapes through valves I6 and i8. The pump is thenstopped, the valves 3, i6 and I8 are closed, and the machine is broughtup to full speed, whereupon the valve 3 can be opened and the pump 4started to circulate oil through the system.

Asthe oil from pipe 2 passes through the purifier 5 all water and heavysolid dirt are thrown out and the purified oil is returned through thepipe 6 to the transformer i. The heavy solids are retained in the purierbowl while the water and v'a little oil rlow to the gravity separatingtank 9. Here the water settles to the .bottom, while a small stream ofoil flows through the pipe i3, at a rate controlled bythe valve Il, backto the pipe 2 at the suction side of the pump 4. When enough water hascollected in the tank 9 it raises the float Il, which opens the valve liand allows the water to escape through the pipe |2. If water ceases toilow from the purifier, valve Il closes but the oil escaping throughpipe i3 maintains a stream that will carry any subsequently separatedwater to tank 9 to cause operation of the float and valve.

y The operation of the apparatus shown in Fig. 2 is the. same as thatshown in Fig. l except'thatA instead of the gravity tank andfloat-operated valve a centrifuge lis used.

Calculations by formulae well known to and constantly used by designersof centrifugal sep-l the pipe |3a will be required to cause lightconstituent to flow out with the heavy constituent.

What I claim, and desire to protect by Letters Patent'is:

l. 'l'hat process for removing impurities from liquids winch aredeieteriously aected by contact with air which comprises establishing aflowing main stream from a body of liquid containing such impurities toa body of puried liquid, centrifugaily separating from such stream asmaller stream containing impurities with some liquid, separating amajor portion of the impurities from `the smaller stream and returningthe remainder of the smaller stream to, and mixing it with, the

impure liquid to be subjected to said centrifugal separation, andmaintaining completely enclosed against admission of air all streamscontaining substantially any of such liquid while flowing toward andaway from said loci of separation and during separation.

2. That process for removing impurities from liquids which aredeieteriously affected by contactwith air which comprises establishing aowing main stream from a body of liquid'containing such impurities to abody of puried liquid, cen-4 trifugally separating from such stream asmaller stream containing impurities with some liquid, separating amajor portion of the impurities from the smallerstream and returning theremainder of the smaller stream to the main stream at a point thereinbetween the body of impure liquid and the locus of centrifugalseparation, and maintaining completely enclosed against admission of airall streams containing substantaliy any of such liquid while owingtoward and away from said loci of separation and during separation.

3. The process of removing impurities from liquids which comprisesestablishing a flowing stream from a body of liquid containing suchimpurities toa locus of centrifugal separation and at said locusseparating puried. liquid from impurities containing some liquid,vconveying such separated piuied liquid from the locus of centrifugalseparation in a second stream`\^to a body of purined liquid, conveyingsaid separated impurities containing some liquid in a third atseparating the bulk of the impurities from the liquid, and conveying theliquid last specified with any impurities contained therein from thesecond locus of separation in a fourth stream to, and mixing it with,the impure liquid to be subjected to said centrifugal separation, andmaintaining completely enclosed against admission of air all streamscontaining substantially any'of such liquid while flowing toward andVaway from said loci of separation and during separation.

4. Apparatus for purifying liquids comprising a centrifugal purifier, aconduit through which a' stream of impure liquid `is adapted to beconducted from a body thereof to said purifier, said f centrifugalpurifier being vadapted to separate heavy impurities with some liquidfrom the liquid to be purified and separately discharge ,a major streamof puried liquid and a minor stream of liquid and impurities, a conduitadapted to conduct said major stream to a body of purified liquid, aseparator adapted to separate impurities from said minor stream, aconduit adapted to convey the remainder o'f said minor stream to theimpure liquid to be subjected to centrifugal. purification, and meanscompletely closing from the atmosphere said)i purifier, said separatorand said conduits, thereby maintaining stream to a second locus ofseparation and theregas-free the impure liquid flowing to the purifier,the liquid being puriiied, both streams of liquid flowing from thepurifier, the liquid being separated in the separator and the liquidflowing from the separator to the first named stream of impure liquid.

5. Apparatus for purifying liquids comprising a source of supply ofimpure liquid, a receiver for purified liquid, a centrifugal purieradapted to separate puried liquid from impurities containing someliquid, a secondv puriiier adapted to separate impurities from liquidcontaining some impurities, and a closed system comprising a closedconduit for impure liquid affording lair tight communication betweensaid source and said centrifugal purifier, a closed conduit forseparated puried liquid `affording air tight coinmunication between saidcentrifugal puriiier and said receiver, a closed conduit for separatedimpurities affording air tight communication between said centrifugalpurifier and said second purifier, an outlet for impurities from thesecond purifier, and a closed conduit alfording air tight communicationfor liquid separated from impurities between the second purier and thefirst named conduit, thereby maintaining the said liquids iiowingthrough all said conduits and the liquids being purified free fromcontamination by air.

6. 'Ihe combination of a centrifugal purifier having an inlet, closed tothe atmosphere, for

impure liquid, an outlet, closed to` the atmosphere, for purified liquidand an outlet, closed to the atmosphere, for liquid impurities, a pumpand conduit, closed to the atmosphere, for feeding to said centrifugalpurifier liquid to be purified, a separation chamber in closedcommunication with the outlet for liquid impurities from saidcentrifugal separator, a throttled passage from the top of said chamberin closed communication with the suction side of said pump, and afloat-controlled opening from the bottom of said chamber.

7. The combination of a centrifugal purifier having an inlet, closed tothe atmosphere, for impure liquid, an outlet, closed to the atmosphere,for puried liquid and an outlet, closed to the atmosphere, for liquidimpurities, a pump and conduit, closed to the atmosphere, for feeding tosaid centrifugal purifier liquid to be purified, a second centrifugalpurifier having an inlet in closed communication with the outlet forliquid impurities from the first purifier, an outlet for heavierseparated constituent and an outlet for separated lighter constituent,and a throttled passage from the last named outlet in closedcommunication with the suction side of said pump, thereby maintainingthe said liquids flow-` ing to, through and from the flrst purier and toand through the second purier and through said passage free fromcontamination by air.

THEODORE H. MIHER..

